At present, using wireless local area networks (WLANs) for data communication has been become very common, and requirements for WLAN coverage in the whole world increase constantly. A series of standards, such as 802.11a/b/g/n/ac, are defined successively by a group of industry specifications IEEE802.11 of the Institute of Electrical and Electronics Engineers to satisfy ever-increasing communication requirements. FIG. 1 is a schematic diagram of a constitution structure of a basic service set (BSS). As shown in FIG. 1, in a common WLAN network, one BSS may be composed of one access point (AP) station (STA) and a plurality of non-AP STAs associated with it. At present, the IEEE802.11 supports two clear channel determine methods, i.e., physical carrier detection and virtual carrier detection. Only when the channel is determined to be clear by using both the physical carrier detection and the virtual carrier detection, the STA can perform competitive sending. Herein, the physical carrier detection means a clear channel assessment (CCA) channel detection technology, that is, the STA determines whether the channel is busy or clear by detecting the strength of signals on media and in conjunction with a CCA threshold value. The virtual carrier detection means that a third party STA except two communication parties sets a value of a local network allocation vector (NAV) according to a value of a duration domain in the wireless frame when receiving a wireless frame, a receiver address of which is not the address of the third party STA. The NAV is a counter, and when the NAV is not zero, it is considered that the channel is busy and the competitive sending will not be performed. Only when the channel is determined to be clear by using both the physical carrier detection and the virtual carrier detection, the STA can compete to access channel for sending.
As devices in the WLAN increase gradually, to increase channel access opportunities, multiplexing transmission is allowed on the same working channel at the same time. FIG. 2 is a schematic diagram of multiplexing transmission. As shown in FIG. 2, a STA A communicates with a STA B. If a STA C can receive signals from the STA B and cannot receive signals from the STA A, then it is considered that the STA C will not interfere with data receiving of the STA A from the STA B. Therefore, the STA C transmits data to a STA D with the same frequency band resources during duration time of the wireless frame currently being transmitted, i.e., while the STA B is communicating with the STA A, to improve network throughput.
However, in actual environments, transmitting powers of the transmitting stations are different, and inequality of the powers between the transmitting stations will cause asymmetry of the coverage area. A problem that the above process faces is that if the STA C communicates with the STA D with higher transmitting power, communication between the STA B and the STA A will be interfered. FIG. 3 is a schematic diagram of high power multiplexing transmission. As shown in FIG. 3, since too high transmitting power of the STA C interferes seriously with data receiving of the STA A, the STA A fails to receive the data. In the existing art, there is no efficient solution yet to such interference caused by the inequality of the transmitting powers.